A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick. Multiple tests for specific blood components (such as a glucose test or a cholesterol test) are often grouped together into one test panel called a blood panel or blood work.
Upper Air Troughs. When the height contours bend strongly to the south, (as in the diagram below), it is called a TROUGH. Strong troughs are typically preceded by stormy weather and colder air at the surface. Here is an example of a trough in an upper-level height field (red contours).
The pressure generated by an overlying column of fluid is thus termed the hydrostatic pressure. The upper boundary of the air column that gives rise to atmospheric pressure is the vacuum of space. Being rather light, the mass of a column of air with a 1 cm 2 cross section is almost exactly 1 kg.